TREND OF DEVELOPMENT
With the rapid development of infrastructure construction in our country, concrete has become an indispensable building material. As an important building material, machine-made sand is in great demand, while natural sand has long been unable to meet the needs of the market.
In some places, serious mining damages farmland and water conservancy resources and seriously affects environmental resources. In this context, the promotion and application of machine-made sand are increasingly valued by people in the industry, and machine-made sand has gradually become the main raw material for concrete mixing plants. The self-built machine-made sand production line has become the mainstream trend of future development in some large concrete mixing plants.
At present, there are more than 20,000 large and small sand and gravel factories in the country, of which 80%-90% have a production scale of fewer than one million tons, and most of them have a production scale of fewer than 300,000 tons. Most of the small sand and gravel factories have simple processes. Sewage and waste discharge are seriously exceeding the standard, and the quality of finished sand and gravel is uneven. Under the triple pressure of environmental protection, supervision, and market demand, it faces the pressure of shutdown and elimination. As a result, the new environmentally friendly and high-quality machine-made sand project will take the east wind of industrial transformation and upgrading and become an irreversible development trend.
Commercial concrete enterprises have traditionally relied on outsourcing machine-made sand, but the quality of machine-made sand varies greatly due to the change of procurement channels, which in turn causes commercial concrete enterprises to frequently adjust the concrete mix ratio, bringing huge risks to commercial concrete products. The self-built machine-made sand production line of commercial concrete enterprises is highly controllable. Due to the use of the machine-made sand production line with the SR series sand-making machine as the core product of Sino-German technical cooperation, the production process and equipment are relatively advanced, which can ensure that the gradation, grain shape, and other physical properties of manufactured sand are more stable. At the same time, because the sand and gravel are all mined from the same source, the chemical properties of the sand and gravel are more stable compared to those in the past, which ensures the stability of the quality of the self-produced machine-made sand to a certain extent. There is also no need to adjust the mix ratio frequently, which reduces the quality problems such as insufficient strength and cracking of the commercial concrete quality, thereby reducing the risk of the enterprise. In addition, the self-built machine-made sand production line can not only ensure the daily sand consumption, and reduce the production cost, but also can be sold, which has good economic benefits.
The total surface area of the sand particles should be small, that is, the sand should be as coarse as possible; in concrete, the cement paste is bonded by the surface of the aggregate particles. The smaller the total surface area of the aggregate, the more economical the cement is.
The particle gradation of the sand is good. Particle gradation refers to the combination of sands with different particle sizes. The size of the sand particles is reasonably matched to achieve step-by-step filling, reducing the porosity, saving cement, and improving the density of concrete, thereby enhancing strength and durability.
Concrete sand includes natural sand and machine-made sand. Natural sand, as a ground material resource that cannot be reborn in a short period of time, is unevenly distributed, and long-distance transportation brings a heavy burden to engineering construction. In addition, due to ecological protection, various mining ban policies have also made the contradiction between the supply and demand of natural sand increasingly prominent. In particular, natural sand with high standards is becoming less and less, and it has become an inevitable trend to replace natural sand with high-quality machine-made sand.
The high-quality machine-made sand has an excellent grain shape, and few needle flakes and most of them are cubes, which increases the contact surface with the cement paste, has good bonding ability, and good workability, and makes the concrete more compact;
The production gradation of machine-made sand is adjustable, and the finished sand produced has a reasonable gradation and a fineness modulus of 2.3~3.0, mainly medium sand;
Less mud content, less mud block content, less admixture for solid concrete;
The initial slump performance of the high-quality machine-made sand is better, the expansion is larger, the loss over time is smaller, and the concrete performance is better.
In short, the application technology of high-quality machine-made sand in concrete is a mature technology, which can improve the working performance of concrete, increase the compressive strength of concrete, and improve the impermeability of concrete.
Take the model SR1222 sand-making machine, crushing 5-100cm limestone, producing 150 tons of machine-made sand per hour, 1500 tons per day, and 500,000 tons per year.
|Total installed power is about 400kW, calculated at 0.8 yuan/KW/hour
|Calculated according to general working conditions, the amount of different raw materials and consumables is different
|The production equipment is folded according to 10 years
|Workers at 6000 yuan/month
|Raw materials cost
|According to the price of 6-8cm limestone in Zhengzhou
|According to the annual output of 500,000 tons, the unit price of high-quality machine-made sand is only calculated at 60 yuan / ton
|Calculated at an annual output of 500,000 tons and a cost of 25.2 yuan per ton
|Calculated at 2% of sales revenue
|Taxes and Dues
|Calculated at 6% of sales revenue
|Calculated at 2% of sales revenue